1. Field of the Invention
This invention relates to a process for the control of enteric bacterial pathogens in animals using expanded matrix materials.
2. Description of the Prior Art
Despite the efforts of researchers and public health agencies, the incidence of human infections from enteropathogenic bacteria such as Salmonella, E. coli 0157:H7, and Campylobacter has increased over the past 20 years. For example, the number of actual reported cases of human Salmonella infection exceeds 40,000 per year. However, the Communicable Disease Center estimates that the true incidence of human Salmonella infections in the United States each year may be as high as 2 to 4 million. The USDA Economic Research Service has recently reported that the annual cost of the food borne illnesses caused by six common bacterial pathogens, Campylobacter spp., Clostridium perfringens, Escherichia coli 0157:H7, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus, ranges from 2.9 billion to 6.7 billion dollars (Food Institute Report, USDA, AER, December, 1996). In addition to the impact of enteric pathogens on human health, many of these bacteria also cause significant infections in animals. For example, Salmonella infections in swine alone cost the United States swine industry more than 100 million dollars annually (Schwartz, 1990, "Salmonellosis in Midwestern Swine", In: Proceedings of the United States Animal Health Assoc., pp. 443-449).
Animal food products remain a significant source of human infection by these pathogens. Contamination of meat and poultry products with many bacterial food-borne pathogens, including the particularly onerous pathogens Campylobacter spp., Escherichia coli 0157:H7, and Salmonella spp., often occurs as a result of exposure of the animal carcass to ingesta and/or fecal material during or after slaughter. Any of the above-mentioned pathogens can then be transmitted to humans by consumption of meat and poultry contaminated in this manner.
Preharvest control of enteropathogenic bacteria is a high priority to the food industry. However, few products have been developed to facilitate such efforts. Currently, preharvest pathogen control within the poultry industry is accomplished through use of competitive exclusion cultures or probiotics. In fact, at this time, only one such product, developed by Nisbet et al. of the USDA Agricultural Research Service (U.S. Pat. No. 5,478,557) and sold under the trademark PREEMPT (Milk Specialties Biosciences, Dundee, Ill.), is available commercially in the United States. Moreover, the administration of competitive exclusion cultures is preferably targeted to very young animals. Immune lymphokines (ILK) have also been recently developed for protecting poultry from colonization with enteric pathogens as described by Ziprin et al. (1989, Poult. Sci., 68:1637-1642), McGruder et al. (1993, Poult. Sci., 72:2264-2271), Ziprin et al. (1996, Avian Dis., 40:186-192), and Tellez et al. (1993, Avian Dis., 37:1062-1070), and more recently by Kogut et al. (U.S. Pat. Nos. 5,891,443 and 5,691,200).
Despite these advances, the need persists for technologies for controlling enteric pathogens in animals, and particularly for the treatment of animals immediately prior to slaughter.